Currently a large number of video cameras which are equipped with monitor screen units configured as casings separate from video camera bodies (hereinafter referred to as VTR units are offered for sale). A video camera equipped with a monitor screen unit which can be positioned horizontal relative to a VTR unit, opens and closes to positions at which it is revolved substantially perpendicular to the VTR unit and rotates around an axis substantially perpendicular to the VTR unit has two rotating shafts which enable the respective rotations. When these two rotating shafts are rotated at the same time, however, a casing of the VTR unit may be brought into contact with an angle portion of the casing of the monitor screen unit, whereby either of the casings may be injured. Further, a video camera equipped with a shaft rotator which does not allow two shafts to be rotated at the same time adopts a rotating shaft control mechanism which occupies a large space in a casing of a VTR unit or an external equipment unit, thereby constituting a hindrance to a compact configuration of the video camera.
A configuration of the rotating shaft control mechanism of the conventional shaft rotator will be described below. Main members of the rotating shaft control mechanism of the conventional rotating shaft rotator are shown in an enlarged perspective view in FIGS. 6a and 6b, wherein a reference numeral 19 represents a first rotating support shaft which is fixed to a VTR unit 1, a reference numeral 20 designates a second rotating support shaft and a reference numeral 21 denotes a fixing plate which is fitted over the shafts and is freely rotatable. A rotating boss 14 is fixed to the fixing plate 21, a rotating shaft 15 passes through the rotating boss 14 in a freely rotatable condition, a monitor screen unit 2 is fixed to one end of the rotating shaft 15 and a rotation control piece 16 is fixed to the other end of the rotating shaft 15. Further, the rotation control piece 16 has a circle-like shape, from which two opposing portions of its contour are linearly cut off, and is equipped on both side faces thereof with a first rotation control plate 17 and a second rotation control plate 18 which are fixed to the VTR unit.
Now, description will be made of operations of the conventional shaft rotator which is configured as explained above.
First, the monitor screen unit 2 is revolved in a direction indicated by an arrow A around the first rotating support shaft 19 and the second rotating support shaft 20. At this time, the rotation control piece 16 which is fixed by way of the monitor screen unit 2 and the rotating shaft 15 is in a condition where it is not rotatable since its linearly cut portions are defined as side faces thereof and sandwiched between the first rotation control plate 17 and the second rotation control plate 18. As a result, the monitor screen unit 2 which is fixed by way of the rotating shaft 15 is also in a condition where it is not rotatable.
When the monitor screen unit 2 is further revolved in the direction indicated by the arrow A until the monitor screen unit is substantially perpendicular to the VTR unit 1 as shown in FIG. 6b, the rotation control piece 16 is set in a condition where it is rotatable in a direction indicated by an arrow B or C since it is positioned at a location where the first rotation control plate 17 and the second rotation control plate 18 are widened, and the monitor screen unit 2 which is fixed against rotation by way of the rotating shaft 15 is also set in a rotatable condition.
Even if it is attempted to rotate the monitor screen 2 in a direction reverse to that indicated by the arrow A while the monitor screen unit 2 is kept turned for about 90.degree. in the direction indicated by the arrow B or C as shown in FIG. 7, arc portions of the rotation control piece 16 which is fixed by way of the monitor screen unit 2 and the rotating shaft 15 are located on sides of the first rotation control plate 17 and the second rotation control plate 18, and the rotation control piece 16 cannot penetrate into a location where the first rotation control plate 17 and the second rotation control plate 18 have a narrower width, whereby the monitor screen unit 2 cannot be revolved in the-direction reverse to that indicated by the arrow A.
However, the conventional shaft rotator which has the configuration described above poses a problem that it hinders video cameras from being configured compact since the shaft rotator requires rotation control mechanisms such as the rotation control piece 16, the first rotation control plate 17 and the second rotation control plate 18 which are accommodated in the casing of the VTR unit, thereby requiring a large space.
The present invention has an object to solve the conventional problems described above and to provide a shaft rotator which is configured to hinder two shafts of a shaft rotator accommodated in a recorder/reproducer unit from rotating at a time and is effective to configure video cameras compact since an internal space of a console of a VTR unit needs not be used.